expression

Documentation

Overview

Package expression implements a Benthos dynamic field expression and the parser combinators for parsing them.

Index

• type Expression
  • func Parse(expr string) (*Expression, error)
  • func (e *Expression) Bytes(index int, msg Message) []byte
  • func (e *Expression) BytesEscaped(index int, msg Message) []byte
  • func (e *Expression) BytesEscapedLegacy(index int, msg Message) []byte
  • func (e *Expression) BytesLegacy(index int, msg Message) []byte
  • func (e *Expression) String(index int, msg Message) string
  • func (e *Expression) StringLegacy(index int, msg Message) string
• type Message
• type Type
  • func New(expr string) (Type, error)

Types

type Expression

type Expression struct {
	// contains filtered or unexported fields
}

Expression represents a dynamic Benthos field expression.

func Parse

func Parse(expr string) (*Expression, error)

Parse a string into a Benthos dynamic field expression.

func (*Expression) Bytes

func (e *Expression) Bytes(index int, msg Message) []byte

Bytes returns a byte slice representing the expression resolved for a message of a batch.

func (*Expression) BytesEscaped

func (e *Expression) BytesEscaped(index int, msg Message) []byte

BytesEscaped returns a byte slice representing the expression resolved for a message of a batch with the contents of resolved expressions escaped.

func (*Expression) BytesEscapedLegacy

func (e *Expression) BytesEscapedLegacy(index int, msg Message) []byte

BytesEscapedLegacy is DEPRECATED - Instructs deprecated functions to disregard index information. TODO V4: Remove this.

func (*Expression) BytesLegacy

func (e *Expression) BytesLegacy(index int, msg Message) []byte

BytesLegacy is DEPRECATED - Instructs deprecated functions to disregard index information. TODO V4: Remove this.

func (*Expression) String

func (e *Expression) String(index int, msg Message) string

String returns a string representing the expression resolved for a message of a batch.

func (*Expression) StringLegacy

func (e *Expression) StringLegacy(index int, msg Message) string

StringLegacy is DEPRECATED - Instructs deprecated functions to disregard index information. TODO V4: Remove this.

type Message

type Message interface {
	Get(p int) types.Part
	Len() int
}

Message is an interface type to be given to a function interpolator, it allows the function to resolve fields and metadata from a message.

type Type

type Type interface {
	// Bytes returns a byte slice representing the expression resolved for a
	// message
	// of a batch.
	Bytes(index int, msg Message) []byte

	// BytesLegacy is DEPRECATED - Instructs deprecated functions to disregard
	// index information.
	// TODO V4: Remove this.
	BytesLegacy(index int, msg Message) []byte

	// BytesEscaped returns a byte slice representing the expression resolved
	// for a message of a batch with the contents of resolved expressions
	// escaped.
	BytesEscaped(index int, msg Message) []byte

	// BytesEscapedLegacy is DEPRECATED - Instructs deprecated functions to
	// disregard index information.
	// TODO V4: Remove this.
	BytesEscapedLegacy(index int, msg Message) []byte

	// String returns a string representing the expression resolved for a
	// message of a batch.
	String(index int, msg Message) string

	// StringLegacy is DEPRECATED - Instructs deprecated functions to disregard
	// index information.
	// TODO V4: Remove this.
	StringLegacy(index int, msg Message) string
}

Type represents a Benthos dynamic field expression, used to configure string fields where the contents should change based on the contents of messages and other factors.

Each function here resolves the expression for a particular message of a batch, this is why an index is expected.

func New

func New(expr string) (Type, error)

New attempts to parse and create an expression from a string. If the expression is invalid an error is returned.